cefclient: views: Support window state restore (see issue #3359)

The cefclient sample app will persist window state across application restart
if run with views, cache_path and persist_user_references enabled.

To test:
1. Run `cefclient --use-views --cache-path=/path/to/cache --persist-user-preferences`
2. Move or resize the window, maximize, minimize, etc.
3. Exit cefclient.
4. Run cefclient again with the same arguments. The previous window state will
   be restored.

tests/cefclient/browser/root_window.h

@@ -25,19 +25,19 @@ struct RootWindowConfig {
   RootWindowConfig();
 
   // If true the window will always display above other windows.
-  bool always_on_top;
+  bool always_on_top = false;
 
   // If true the window will show controls.
-  bool with_controls;
+  bool with_controls = true;
 
   // If true the window will use off-screen rendering.
-  bool with_osr;
+  bool with_osr = false;
 
   // If true the window is hosting an extension app.
-  bool with_extension;
+  bool with_extension = false;
 
   // If true the window will be created initially hidden.
-  bool initially_hidden;
+  bool initially_hidden = false;
 
   // Requested window position. If |bounds| and |source_bounds| are empty the
   // default window size and location will be used.
@@ -49,6 +49,10 @@ struct RootWindowConfig {
   // based windows when |initially_hidden| is also true.
   CefRect source_bounds;
 
+  // Requested window show state. This is currently only implemented for Views-
+  // based windows when |bounds| is non-empty and |initially_hidden| is false.
+  cef_show_state_t show_state = CEF_SHOW_STATE_NORMAL;
+
   // Parent window. Only used for Views-based windows.
   CefRefPtr<CefWindow> parent_window;